Power wrench



April 15, 1969 R. S. HAYES, JR

POWER WRENCH Filed June 5, 1967 3?. EH a 33 34 d a? as INVENTOR.

RALPH s. HAYES JR.

%M w. r\ W ATTORNEY United States Patent 3,438,451 POWER WRENCH Ralph S. Hayes, Jr., Waverly, N.Y., assignor to Ingersoll- Rand Company, New York, N.Y., a corporation of New Jersey Filed June 5, 1967, Ser. No. 643,674 Int. Cl. EZlc 1/12; B25b 21/02; Flllb 3/00 US. Cl. 173-163 Claims ABSTRACT OF THE DISCLOSURE A two-speed power wrench including a casing rotatably mounted on a support and containing a rotary motor driving a spindle adapted to be connected to a fastener. A fluid-powered piston motor is mounted at the top end of the casing with the piston axis aligned with the casing axis and with a cam connection between the piston and the casing for converting the reciprocating motion of the piston to a rotary motion of the casing. The rotation of the casing is transmitted to the spindle through a unidirectional clutch which allows the rotary motor to drive the spindle freely in a fastener tightening direction while allowing the casing to drive the spindle after the rotary motor is stalled.

Background of the invention This invention relates to two-speed power wrenches having a high speed for running down a fastener and a low speed for tightening the fastener to a high torque load.

In general, prior art two-speed power wrenches capable of tightening fasteners to high torque loads have been relatively bulky. This hulkiness interfered or prevented them from being mounted relatively close to one another as a cluster, which is highly desirable in machines used to drive a plurality of fasteners simultaneously.

Summary of invention The principal object of this invention is to overcome the foregoing disadvantages of the prior art and to provide a two-speed power wrench having a relatively narrow elongated shape which is adapted to be mounted relatively close to other power wrenches of the same design without interference between the wrenches.

Other important objects of this invention are: to provide a power wrench with a low speed, high torque jacking system which fits on the end of the power wrench and does not increase its width; and to provide a power wrench with a novel high torque jacking system.

In general, these objects are attained in a two-speed power wrench having a high speed rotary motor driving a spindle by mounting a high force reciprocating fluid motor in line with the rotary motor and spindle to provide the wrench with a relatively narrow appearance. The reciprocating fluid motor is connected to the rotary motor casing by a cam means which converts the reciprocation of the reciprocating motor to a rotary oscillation of the casing. The casing is connected to the spindle by a unidirectional clutch which drives the spindle in a single rotary fastener-tightening direction.

Brief description of drawing The invention is described in connection with the accompanying drawings wherein:

FIG. 1 is an elevational view, having portions broken away and shown in section, of a power wrench illustrating the concepts of this invention;

FIG. 2 is a fragmentary elevational view taken on line 2-2 of FIG. 1; and

FIG. 3 is an enlarged section taken on line 3-3 of FIG. 1.

Description of preferred embodiment The power wrench 1 includes a wrench casing 2 rotatably mounted on a support 3 by a bearing 4. The bearing 4 can be a conventional thrust bearing which supports the weight of the wrench while allowing the wrench casing 2 to rotate on the support 3. The casing 2 is guided and centered on the bearing 4 by several rollers 4' rotatively mounted on the support 3 and engaging the casing 2. The casing 2 is hollow and carries a rtoary motor 5 driving a spindle 6 provided at its lower end with flats 7 adapted to fit in a conventional wrench socket 8 (shown in dotted lines). The motor 5 is of the type that can be stalled without damage, such as a fluid motor. The motor 5 is illustrated as a pneumatic motor supplied through the hose 9. The spindle 6 includes two telescoping portions, an upper hollow shaft 11 rotatably mounted in two pair of ball bearings 12 and keyed to the motor rotor 13 and a lower stub shaft 14 slidably keyed in the hollow shaft 11 by a cross pin 15 extending through a longitudinal slot 16 in the stub shaft 14. A spring 17 is placed inside of the hollow shaft 11 to urge the stub shaft 14 downwardly or forward.

The spindle 6 is connected to the casing 2 by a unidirectional clutch 20' disposed between the hollow shaft 11 and the inside of the casing 2. The unidirectional clutch 20 may be of several different types. In the drawing, the clutch 20 is of the sprag type and includes an outer race 21, an inner race 22 and a plurality of sprags 23 disposed between the races 21 and 22. The sprags 23 are shaped so that they will wedge between the races when the casing 2 is rotated clockwise relative to the spindle 6, as shown in FIG. 3, so that the casing will drive the spindle 6. The sprags 23 unwedge and allow the spindle 6 to rotate clockwise relative to the casing 2. Thus the motor 5 can run down a fastener, until it stalls without interference from the casing 2.

A fluid-powered reciprocating motor 26 is mounted over the upper end of the casing 2 and on the support 3. The motor 26 includes a cylinder 27 containing a sliding piston 28 and is positioned with the axis of the piston 28 substantially aligned with the axis of the spindle 6. By positioning the motor 26 in this manner, the shape of the power wrench 1 retains its slim elongated appearance. A slim shape is advantageous because it allows a number of the power wrenches 1 to be grouped together in a relatively tight cluster, which is often necessary in machines which simultaneously tighten a plurality of fasteners.

The forward end of the cylinder 27 is mounted on the support 3 by a table-shaped frame 30 having legs 31 extending from the cylinder 27 and attached to the support 3. The frame 30 includes a pair of diametrically opposed longitudinally extending slots 32, a slot 32 being formed in each leg 31. The piston 28 includes a piston rod 33 connected to a crosshead 34 having respective rollers 35 riding in each of the slots 32 as the piston 28 reciprocates. The frame 30 surrounds the upper end portion 36 of the casing 2. The upper end portion 36 is pro vided with a pair of diametrically opposed helical slots 37 surrounding and engaging the rollers 35. Due to the fact that the slots 37 are helically shaped, the linear reciprocation of the crosshead rollers 35 in the frame slots 32 will rotate the casing 2 back and forth. This back and forth oscillation of the casing 2 will be transmitted through the unidirectional clutch 20 to the spindle 6 as a rotary jacking motion acting in a single direction to tighten a fastener.

To operate the power wrench 1, the operator manipulates the sup-port 3 to position the wrench socket 8 on a fastener and then opens a valve, feeding air pressure to the rotary motor 5. Simultaneously, he may manipulate a control which causes the piston motor 26 to begin continuous reciprocation. No attempt is made to describe the fluid system for operating the piston motor 26 because it is conventional and well known to those skilled in the art.

Initially, the rotary motor 5 will run down the fastener. The oscillation of the casing 2 by the piston motor 26 will not slow or otherwise effect the operation of the rotary motor 5, due to the fact that the rotary motor 5 will rotate faster than the casing in the fastener tightening direction.

After the rotary motor 5 stalls, the continued oscillation of the casing 2 will rotate the spindle 6 in the fastener tightening direction until the fastener is either so tight that it stalls the piston motor 26 or the piston motor 26 is stopped by a torque sensing device. Preferably, the operation of the wrench 1 is stopped by a torque sensing mechanism which measures the torque load on the fastener and stops the wrench 1 when the torque load rises to a selected value.

Although only one embodiment of the present invention has been shown and described, it should be understood that the invention is not limited thereto except by the scope of the claims. Various modifications and changes can be made without departing from the scope and spirit of the invention as the same will now be understood by those skilled in the art.

I claim:

1. A power wrench comprising:

a wrench body rotatively mounted on a support;

a rotary motor mounted in said wrench body;

a spindle rotatively mounted in said body and connected to said motor to be driven thereby, said spindle being adapted to be connected to a fastener for driving the fastener;

a unidirectional clutch interconnected between said spindle and said wrench casing and arranged to allow said spindle to rotate in a fastener-tightening direction relative to said wrench casing;

a reciprocating power means mounted on said support and having a reciprocating power member moving along a path substantially in alignment with the axis of said spindle; and

power converter means interconnecting said power member to said wrench casing and operative to convert the reciprocating motion of said power member to a rotary motion of said Wrench casing.

2. The power wrench of claim 1 wherein:

said rotary motor is of a type adapted to be stalled.

3. The power wrench of claim 2 wherein:

said rotary motor is a fluid powered motor.

4. The power wrench of claim 1 wherein:

said power means includes a cylinder and said power member is a piston sliding in said cylinder and driven by fluid pressure.

5. The power wrench of claim 1 wherein:

said power converter means includes a cam and a cooperating cam follower causing said wrench body to oscillate.

References Cited UNITED STATES PATENTS 1,353,275 9/1920 Schneider 92-31 2,893,278 7/1959 Rice 8l52.4 2,952,176 9/1960 Mitchel 8l52.4 3,391,722 7/1968 Ligh 92-31 X ERNEST R. PURSER, Primary Examiner. 

